Transit of Venus today may reveal the "Mysterious Arc of Venus"

Three photos from the Arc of Venus observed during the planet’s 2004 transit by amateur astronomer near Toulouse, France. Image Courtesy of André Rondi.

When Venus transits the sun on June 5th and 6th, an armada of spacecraft and ground-based telescopes will be on the lookout for something elusive and, until recently, unexpected: The Arc of Venus.

“I was flabbergasted when I first saw it during the 2004 transit,” recalls astronomy professor Jay Pasachoff of Williams College. “A bright, glowing rim appeared around the edge of Venus soon after it began to move into the sun.”

For a brief instant, the planet had turned into a “ring of fire.”

Researchers now understand what happened. Backlit by the sun, Venus’s atmosphere refracted sunlight passing through layers of air above the planet’s cloudtops, creating an arc of light that was visible in backyard telescopes and spacecraft alike.

It turns out, researchers can learn a lot about Venus by observing the arc. Indeed, it touches on some of the deepest mysteries of the second planet.

The arc of Venus photographed in 2004 by Riccardo Robitschek and Giovanni Maria

Caglieris of Milan, Italy. “We do not understand why our sister planet’s atmosphere evolved to be so different than Earth’s,” explains planetary scientist Thomas Widemann of the Observatoire de Paris.

Earth and Venus are similar distances from the sun, are made of the same basic materials, and are almost perfect twins in terms of size. Yet the two planets are wrapped in stunningly dissimilar blankets of air. Venus’s atmosphere is almost 100 times more massive than Earth’s and consists mainly of CO2, a greenhouse gas that raises the surface temperature to almost 900°F. Clouds of sulfuric acid tower 14 miles high and whip around the planet as fast as 220 mph. A human being transported to this hellish environment would be crushed, suffocate, desiccate, and possibly ignite.

For the most part, planetary scientists have no idea how Venus turned out this way.

“Our models and tools cannot fully explain Venus, which means we lack the tools for understanding our own planet,” points out Widemann. “Caring about Venus is caring about ourselves.”

One of the biggest mysteries of Venus is super-rotation. The whole atmosphere circles the planet in just four Earth days, much faster than the planet’s spin period of 243 days. “The dynamics of super-rotation are still a puzzle despite a wealth of data from landmark missions such as NASA’s Pioneer Venus, Russia’s Venera and VEGA missions, NASA’s Magellan and more recently ESA’s Venus Express.”

› View larger The arc of Venus as seen by NASA’s TRACE spacecraft in 2004. Credit: NASA/Trace/LMSAL

This is where the Arc of Venus comes in. The brightness of the arc reveals the temperature and density structure of Venus’s middle atmosphere, or “mesosphere,” where the sunlight is refracted. According to some models, the mesosphere is key to the physics of super-rotation. By analyzing the lightcurve of the arc, researchers can figure out the temperature and density of this critical layer from pole to pole.

When the arc appeared in 2004, the apparition took astronomers by surprise; as a result, their observations were not optimized to capture and analyze the fast-changing ring of light.

This time, however, they are ready. Together, Pasachoff and Widemann have organized a worldwide effort to monitor the phenomenon on June 5th, 2012. “We’re going to observe the arc using 9 coronagraphs spaced around the world,” says Pasachoff. “Observing sites include Haleakala, Big Bear, and Sacramento Peak. Japan’s Hinode spacecraft and NASA’s Solar Dynamics Observatory will also be gathering data.”

Pasachoff has some advice for amateur astronomers who wish to observe the arc. “The best times to look are ingress and egress–that is, when the disk of Venus is entering and exiting the sun. Ingress is between 22:09 and 22:27 UT on June 5th; egress occurs between 04:32 and 04:50 UT. Be sure your telescope is safely filtered. Both white light and H-alpha filters might possibly show the arc.”

“Earth and Venus are similar distances from the sun”
Why is this completely untrue statement so commonly spoken or written? Venus is around 30% closer to the sun and receives ~9x the energy from the sun. That’s about as dissimilar as you can get.

“Earth and Venus are similar distances from the sun, …”
“Our models and tools cannot fully explain Venus, which means we lack the tools for understanding our own planet,” points out Widemann.”
If NASA’s tools currently indicate Venus and the Earth are at similar distances from the sun, perhaps the first tool that should be acquired by NASA is a brain.
George V.

“Our models and tools cannot fully explain Venus, which means we lack the tools for understanding our own planet,” points out Widemann. “Caring about Venus is caring about ourselves.”
How dare he, the science is settled, our models can predict what the Earth’s atmosphere will do with utter precision. Ignore the last 15 years or so of no warming, that’s a minor glitch that will soon be ‘adjusted’ out.
JS

Just a couple of comments, here:
“…Earth and Venus are similar distances from the sun…”
WTF?
Venus, 67.2 million miles from sun.
Earth, 93 million miles from sun.
Difference of 25.8 million miles.
That’s a “similar distance”?
“…Yet the two planets are wrapped in stunningly dissimilar blankets of air. Venus’s atmosphere is almost 100 times more massive than Earth’s and consists mainly of CO2, a greenhouse gas that raises the surface temperature to almost 900°F…”
…while the Earth’s atmosphere consists mainly of water vapor – and CO2 levels are on the order of parts per million, and beneficial to life on our planet.
They’re just trying to get in the usual “CO2 causes the heat there, it must be the cause of the heat on Earth.
Closer to the heat source doesn’t matter.
“…Our models and tools cannot fully explain Venus, which means we lack the tools for understanding our own planet,” points out Widemann. “Caring about Venus is caring about ourselves…”
We care about Venus – we really do. Climate Scientist Bill McKibben is trying to connect the dots now, and insisting that the CO2 levels on Venus are brought back down to the magic 350ppm.
BTW, if a planet can have that much CO2 naturally, where did it all come from?

Venus is water free and there was no dry process to convert the CO2 to O2 as happened on earth. Biological processes need water to work. Earth could have had the same dense atmosphere if it were not sequestered into the rocks as limestone.
I will argue with the super GHG cause of Venusan heat. That dense atmosphere is affected by the gravity which will add heat due to adiabatic compression. This works on Jupiter which emits far more heat than it receives and has an atmosphere of hydrogen/helium. A simple application of the combined gas laws will produce the required temperature without any GHG theory.

blogagog says: June 5, 2012 at 4:08 am
“Earth and Venus are similar distances from the sun”
Why is this completely untrue statement so commonly spoken or written? Venus is around 30% closer to the sun and receives ~9x the energy from the sun. That’s about as dissimilar as you can get.
Only about twice the energy.“Venus’s atmosphere is almost 100 times more massive than Earth’s and consists mainly of CO2, a greenhouse gas that raises the surface temperature to almost 900°F.”
The high temperature has little to do with CO2, and everything to do with the surface pressure. Using the adiabatic lapse rate for the Venusian atmosphere, if you ascend to where the pressure is 1 bar, earth normal, the temperature isn’t that far off from ours, especially considering the greater insolation. If our air atmosphere were at 90 bar, we’d be red hot, too.

-CLICK-
The sound of another brain turning off on hearing (yet again) the unproven claim that Venus’ surface temperature is due to a “greenhouse effect”. Wanna change that? Show me!
“we lack the tools for understanding our own planet”. Yep. That you have shown me, over and over!

ddddd
That’s to replenish the shortage of “d”s.
“A human being transported to this hellish environment would be crushed, suffocate, desiccate, and possibly ignite.”
“A human being transported to this hellish environment would be crushed, suffocated, desiccated, and possibly ignited.”
No problem, don’t mention it. You’re welcome.

henrythethird says:
June 5, 2012 at 4:35 am
“BTW, if a planet can have that much CO2 naturally, where did it all come from?”
Why Big Oil and Big Coal of course! Their slimy tentacles of death, misery, and corporate profits aren’t merely limited to Mother Gaia alone!

Venus is 2/3 the distance from the sun as the Earth. Intensity goes as the inverse of the square of the distance, so Venus receives 9/4 the solar input as the Earth. (sarc)Of course climate science has told us that the sun has no effect on temperature so it obviously must be the CO2 that makes the difference(/sarc).
Seriously, has Hanson infected EVERYTHING at NASA?

There is greater than a random chance that scientists will be compelled to use Venus as a tale of caution regarding our own CO2 output. I believe what they are hoping to discover is not basic science about Venus’ atmosphere, but biased science about ours.

I find the replies to this article very interesting and look forward to reading many more.
When asked about the ‘runaway greenhouse’ effect on Venus I have always answered that Venus is 30% closer to the sun and shoud be even hotter than it is. I put this down to the dense atmosphere reflecting much of the heat and light back into space (making Venus a very bright object in the sky). As Venus has been the way it is for a long time one would have thought a runaway greenhouse effect would have made it much, much hotter by now (even without heating due to the dense atmosphere, as I am reading above).
I am ready to be corrected on any of this, of course.

I could be wrong but I vaguely recollect that Co2 means nothing without the atmospheric pressure. Off the top of my head I think Mars is 95% Co2 and is a ‘similar’ distance to the sun (tongue in cheek).

NASA is clearly short of funding if it lacks the tools to discover that Venus and Earth are at similar distances from the Sun. If that were so we would periodically have a spectacular view of that planet looming up, not to mention the eventual spectacular collision. Venus is about 1/3 (67/93) closer to the Sun than Earth.
They also need extra funding to discover that CO2 does not cause absolutely everything including warming. A few more tools and they could check out the effect that the pressure has on the Venusian temperature. They could also investigate the water on Earth that is lacking on Venus.
This all just looks like yet another attempt to push the CAGW bandwagon out of the mud.

A planet’s atmosphere should have a maximum temperature gradient. This would be determined by the point at which the density of the atmosphere at the surface becomes such that it floats upward and convection starts. Convection removes heat from the planet’s surface faster than any other process. Once convection starts, it takes much more energy to produce a degree of warming at the surface. Venus has a much denser atmosphere than Earth so its atmosphere should have a greater temperature at the surface.

“Venus’s atmosphere is almost 100 times more massive than Earth’s and consists mainly of CO2, a greenhouse gas that raises the surface temperature to almost 900°F.”
From what I can remember, the atmospheric pressure on Venus is 90 times that of Earth’s. This causes CO2 to become a more potent GHG. Yet, with that said, I remember talk of it not even being Venus’ main greenhouse driver. That distinction went to the thick sulfuric acid cloud layer, that allows Venus to see far less sunlight than here on Earth.
So what does that say about CO2 as a greenhouse driver, when it is not only a much more potent GHG in that enviroment, making up 96% of the atmosphere, but is still not the main green house driver?

@Jer0me “So there is 100x Earth’s atmosphere on Venus, making it extremely dense, but it’s not that making it hot, it’s CO2? Codswallop.”
CO2 does contribute, as does 100x Earth’s atmosphere and 9x Solar radiation.
CO2 is definitely a major contributing factor to the heat on its surface but it is 2760X the CO2 on Earth percentage-wise and since Venus has 100x our atmosphere, 276,000X the CO2 on Earth in absolute terms. When that much CO2 keeps in 9X the solar radiation, it should make things a little warmer.

I think the term ‘similar distances’ is fair. As the closest planet to Earth, Venus’ distance from the sun is ‘similar’ to Earth’s more so than any other planet. Of course, the difference matters since Venus receives about twice the solar energy per unit area that Earth does.
IIRC, Venus also has 4 times the amount of nitrogen than Earth. Earth may have lost 3/4 of it’s atmosphere in the collision that created the moon. The remaining CO2 on Earth was mostly converted to carbonates by chemical and biological processes in the oceans. Venus never had liquid water and thus retains it’s primordial CO2 atmosphere. It’s not Venus that’s odd, it’s Earth.
As far as water on Venus, the story I heard was that the water molecules were split into hydrogen and oxygen, with the hydrogen leaving the atmosphere and the oxygen oxidizing the rocky surface. I wonder. If Venus started out with four times the water found on Earth, then that’s a lot of oxygen. It would have to have penetrated the surface very deeply to be completely chemically bound to the rocks.

Venus’s atmosphere is almost 100 times more massive than Earth’s and consists mainly of CO2, a greenhouse gas that raises the surface temperature to almost 900°F.
============
The atmosphere of both Mars and Venus is mainly CO2. One is very hot, the other very cold. This difference is much greater than can be explained by the difference in radiation due to their distance from the sun.
Jupiter, which is much farther away from the sun than Venus, has a much higher surface temperature than Venus. At an atmospheric pressure of about 10 earth atmospheres, temperatures on Jupiter are similar to those of Earth. Yet Jupiter is much farther away from the sun than earth.
None of this can be explained in terms of greenhouse gas. The common factor is the amount of atmosphere and the distance from the sun. The more atmosphere, the warmer the surface. The more solar radiation, the warmer the surface.
Keep in mind that gas molecules do not travel in straight lines. They travel in a curved trajectory under the influence of gravity, and this curved trajectory has minimum kinetic energy at the top of the trajectory and maximum kinetic energy at the bottom of the trajectory.
Thus, the temperature of a single gas molecule changes as it moves under the influence of gravity, independent of any external radiation, and reaches a maximum the lower it travels in the atmosphere. We observe this as the atmospheric lapse rate, which is present on all planets with atmosphere.

Yes, the article is written to suck anyone not paying attention to skeptical arguments into thinking that “there but for the grace of God go I.” Hence, the claim of being similar distances from the sun and the mention of CO2. Although the line “A human being transported to this hellish environment would be crushed, suffocate, desiccate, and possibly ignite,” was interesting, I hope the hopelessly addicted CO2 worshipers aren’t driven to despair by it.
Minor point, but the picture is initially confusing, and even after figuring out that the little arc is Venus in the three pictures, it’s not clear how Venus could be moving into the sun in the order they’re presented. Either Venus is exiting the sun’s arc in the sequence, or, if entering, the pictures are presented in reverse order. The article refers to moving into the sun (“A bright, glowing rim appeared around the edge of Venus soon after it began to move into the sun,”) but the pictures as presented would appear to represent its exiting the sun.
It’s also confusing because the sun is blacked out. Some labeling would have been helpful, as well as a caption indicating that in the sequence Venus is leaving the sun (or reverse the sequence to agree with the text.) Frankly, at first I thought the large ring was Venus in front of the sun (like the recent moon pix) and the arc was some strange phenomenon in the atmosphere of Venus. It took reading the article to sort it all out.

Take a look at the ESA data, only the temperature of the surface layer is high, over 700 K.
Velocities at the surface are low due to the high density, almost no upward convection.
The atmosphere resembles a solar saline heat pond, not heated by sunlight but by the planet’s surface, there is volcanic activity.

“Our models and tools cannot fully explain Venus, which means we lack the tools for understanding our own planet,” points out Widemann.
============
You cannot understand because you are trapped in the equation CO2 = GHG = Temperature.
You have ignored the more fundamental equation. Gravity + Mass = Kinetic Energy = Temperature

All the factual errors and misstatement of facts pointed out by previous commenters make me wonder what’s going on at NASA. It’s obvious Dr. Tony Phillips (whatever his doctorate is in, it certainly has nothing to do with astronomy) doesn’t have anyone fact check his output. This is actually embarrassing.
Jay Davis

John Marshall says:
June 5, 2012 at 4:55 am
“Venus is water free…”
My understanding is that the present understanding (another way of saying that we’re looking at layers of guesswork here) is that our water came from outer space in the form of comets pummelling the Earth for a couple of quintillion years. Since Venus is a “similar” distance, why is it water free?
I’m not snarking (I’ve got Comics Curmudgeon for that) — I’m asking for real.

I understood that Earth’s early atmosphere was very like Venus’ current atmosphere in composition and mass. The most crucial difference was the presence of oceans of water on Earth. This enables the combination of CO2 with calcium and manganese, eventually sequestering most of the CO2 as carbonate minerals, leaving Earth’s atmosphere dominated by nitrogen.

It´s because of a “flabbergasted” consensus which impedes thinking out of a “convenient” box. Time to revisit TODAY, as Venus crosses the Sun, the persecuted and “indexed” work of Immanuel Velikovsky “Worlds in Collision”

Interestingly enough, at the 92 atmospheres of pressure at the surface of Venus, carbon dioxide could best be called a supercritical fluid rather than a gas. Perhaps its atmosphere could better be referred to as an ocean. Here’s a link to the phase diagram and critical point. Cheers –http://www.science.uwaterloo.ca/~cchieh/cact/c123/phasesdgm.html

Venus does not have a magnetic field then it cannot spin as fast as the earth, however its atmosphere, being ionized generates a corresponding magnetic field so it spins faster:
Why do planets spin?: (Warning: You will be committing a SIN against the “Consensus Church” if you see the following) 🙂http://youtu.be/EkU_JmtH3PU

Flabbergasted when he (they) first saw it??
Is anyone else flabbergasted that it wasn’t immediately quite obvious that he was observing
refracted light— and perhaps they should be looking for refraction of other frequencies of EM
waves.

Venus’s atmosphere is almost 100 times more massive than Earth’s and consists mainly of CO2, a greenhouse gas that raises the surface temperature to almost 900°F.

The good Dr. Phillips probably got his Venus info from Wikipedia …or Hansen.
I think he would get a strong argument from Dale Huffman. http://theendofthemystery.blogspot.com/ regarding the cause of high temps on Venus.

Christopher Simpson says:
June 5, 2012 at 9:13 am
John Marshall says:
June 5, 2012 at 4:55 am
“Venus is water free…”
My understanding is that the present understanding (another way of saying that we’re looking at layers of guesswork here) is that our water came from outer space in the form of comets pummelling the Earth for a couple of quintillion years. Since Venus is a “similar” distance, why is it water free?

One suggestion was that the battle to cool Venus down enough for water to hang around was lost early on, and it “boiled away”, breaking down in the upper atmosphere and losing the hydrogen to space.
Associated questions: where did the O2 for the CO2 come from? Maybe from the early water. So where did the C for the CO2 come from? Maybe the carbonaceous chondrites that made up much/part of the early asteroidal material that made up the planet.
Multifaceted mysteries abound …

Brian H says:
June 5, 2012 at 10:02 am
One suggestion was that the battle to cool Venus down enough for water to hang around was lost early on, and it “boiled away”, breaking down in the upper atmosphere and losing the hydrogen to space….
Thanks, Brian. I did wonder about that. I guess our “similar” distances from the Sun aren’t quite so similar after all.
Of course, now there’s the question of why Mars doesn’t have any water, since it was likely bombarded as heavily as Earth by the comets. Would the explanation here be that it’s lower gravity worked against the creation of an atmosphere of sufficient density to stop the water from boiling away in vacuum?

John Marshall says: …I will argue with the super GHG cause of Venusan heat. That dense atmosphere is affected by the gravity which will add heat due to adiabatic compression. This works on Jupiter which emits far more heat than it receives and has an atmosphere of hydrogen/helium. A simple application of the combined gas laws will produce the required temperature without any GHG theory.
Oh, jeez, here we go again.
jayhd says: …It’s obvious Dr. Tony Phillips (whatever his doctorate is in, it certainly has nothing to do with astronomy) doesn’t have anyone fact check his output….
Based on Venus and Earth having “similar” distances from the sun, my guess is Tony is an astrophysicist. They’re happy if the decimal point is in the right place.
adolfogiurfa says: …Time to revisit TODAY, as Venus crosses the Sun, the persecuted and “indexed” work of Immanuel Velikovsky “Worlds in Collision”
They’re not persecuted; they’re ignored as absolute drivel. And they are not in the Vatican’s Index Librorum Prohibitorum, either.

darrylb says: Is anyone else flabbergasted that it wasn’t immediately quite obvious that he was observing refracted light— and perhaps they should be looking for refraction of other frequencies of EM waves.[?]
Right! You can see the same thing in satellite photos of Earth, only it’s light blue.

Venus and Earth receive about the same radiation from the sun as Earth has a lower albedo, thus less radiation is reflected from the surface and clouds than Venus which receives more radiation but also reflects more due to the high sulfuric acid clouds, which are actually pretty thin less than 0.15% of the atmosphere if I recall correctly.
At work I have several gas tanks that are at twice the pressure of the atmosphere of Venus and they are at room temperature.
Venus also has almost 100 times as much deuterium as found elswhere in the solar system including earth, and it got that much because all the water on the surface evaporated and ultraviolet light from the sun hydrolyzed the water vapor into hydrogen and oxygen and the lighter isotope of hydrogen escaped into space at a higher rate than the deuterium.
thanks

The distances are, indeed, very similar, relatively speaking, when measuring planet distances in AU’s. Note that things cannot “ignite” without O2. Lots of guessing going on here as there are too many processes and potential processes that could have affected how Venus became what it is. Going home to try to get some pics of this through the telescope, if it doesn’t cloud up.

I imaged the Venus arc in 2004 using a refractor telescope and webcam.
see http://arnholm.org/astro/venus/
Be very, very careful with this kind of thing. You can easily go blind if you do something wrong. It has to be imaged without a solar filter, and it is definitely not recommended for people who don’t know what thay are doing. You have been warned.

Unfortunately we are going to be rained out and not get to see it. We were going to set up all the university’s solar telescopes to view it too. However we need the rain more than the view.
Jim G: is .67AU similar to 1AU? I suppose if you round to the nearest whole number it is. The rest is good.
I can’t find it now, but whoever commented that their two atmosphere tanks were at room temperature: When those tanks were filled and the gas was compressed into them from atmospheric pressure, those tanks were HOT (provided they were filled quickly enough to not lose the heat at the same rate as it collected). They cooled to equilibrium after time. If you take an IR meter with you to a dive shop when the compressor is filling a tank, you will see the tank is warmer than the surrounding air. I hate when people try to use compressed air tanks as an argument about pressure not equaling temp. Also, your 2ATM tanks are sitting isolated from the weight of atmosphere above them and only have a meter or so of adiabatic change – which would be unmeasurable. If the whole atmosphere were 2ATM instead of 1, the lapse rate would be higher.

ferd berple says:
June 5, 2012 at 8:07 am
Thanks Ferd
When you take time out to add together (a) TSI (b) gravity-induced atmospheric pressure, the whole issue of atmospheric planets’ temperatures becomes obvious, simple, and finally within reach of the calculable from theory.
Again, this goes straight back to my current work on Graeff’s hard experimental evidence leading to the need for a modified restatement (NOT abolition) of the Second Law. Second article coming presently at TT, set against the background of the history and current (academic-research) state of play w.r.t. challenges to the 2LoT. Nothing velikovsky-like, just the familiar workings of straightforward science.
IOW I may, like Monckton, lack formal qualifications, but that does not preclude good scientific attitude, reasonable scientific awareness, the ability to study the necessaries, or the ability to listen to relevant evidence and modify my views accordingly.

Why do planets spin?: (Warning: You will be committing a SIN against the “Consensus Church” if you see the following) 🙂
My guess is that this type of anti-science post is designed to question the scientific validity of this website – by implying that sceptics believe the earth spins because its a magnet.
Yes, that you have a video of a simple electric motor – powered by the battery (the copper wire contacts the battery on the negative terminal, the the magnets contact the battery on the positive terminal, and the current flowing creates a magnetic field that in the wire that pushes the wire around the magnet at the base of the battery. The trick is that the contact at the base of the battery is pulled first one direction, then the other while the wire is spinning so that the magnetic field in the wire is always kept in opposition to the magnetic field of the magnets that the battery is sitting on.
You can’t possibly conflate the magentic field of the earth with the current flow from the battery though. There is simply no comparison. Sure, the earth has a magentic field, but for the motor to work, it has to have two opposing magnetic fields that always work against each other. Where is the second field? Even if there was a second field, it would have to be alternated to make a working motor out of it. Either the earth’s poles would need to flip every 12 hours, or the magnetic force its working against would have to flip every 12 hours. Even if you said that magnetic field came from the sun, I would think it would be more likely to shrink earth’s orbit than to induce spin.

OK if it turns out that the temperature of Venus is found to be far cooler than expected, how many NASA staff will be reading up on Immanuel Velikovsky?
Also if there are obvious gravitational anomalies with an increase in earthquakes, volcanic activity and the odd extra tsunami over the next year, how many will be reading up on Maurice Allais?

Does anyone have a comment on what I found most interesting?
That is– using earth days as a unit of measure, the atmosphere spins around Venus in
just four days. It seems that much could be concluded from that fact.
(not that I have anything to offer at this point)

Here’s a quickie, just after second contact. I managed not to perfect focus so its a little off. I got a few more shots off before the trees swallowed it. ETX90 and a 1000 Oaks filter into my ol’ Nikon 950… Same stuff I used 8 years ago…. eek! Didn’t have much time this year to set something more elaborate.http://ephemerata.ca/uploads/2012Venustransit2nd.jpg

Lucy Skywalker says:
June 5, 2012 at 2:25 pm
ferd berple says:
June 5, 2012 at 8:07 am
Thanks Ferd
When you take time out to add together (a) TSI (b) gravity-induced atmospheric pressure, the whole issue of atmospheric planets’ temperatures becomes obvious, simple, and finally within reach of the calculable from theory.
================
It all became obvious to me when I imagined a single “average” gas molecule.
Now what happens when this molecule impacts the surface? It rebounds in a perfectly elastic fashion, on average gaining energy or losing energy from the surface, based on the relative kinetic energy (temperature) of the gas molecule and the surface molecule.
This molecule then travels upwards from the surface at a velocity determined by its kinetic energy (temperature). However, a strange thing happens. Unless it collides with another molecule, the gravity of the earth slows the velocity of the gas molecule as it travels upwards, decreasing its kinetic energy (temperature).
Now the gas molecule begins to fall back towards the earth. As it falls it gains speed (unless it collides with another molecule) and as it gains speed it gains kinetic energy and thus its temperature increases, until it contacts the surface and the process begins again.
Add up the number of molecules, times their kinetic energy, divide by volume and that gives you the temperature you see on a thermometer. Increase the number of molecules per unit of volume, while leaving the kinetic energy the same, you increase the temperature.

Blogagog,
“Venus is around 30% closer to the sun and receives ~9x the energy from the sun.”
It would have to be 66% closer to receive 9 times the insolation. If it were 30% closer it would get only double the energy per area.
For you who do not think that the CO2 on Venus is responsible for it’s higher temperatures you don’t seem to realize that not only is the Venusian ATM 100 X denser it is also mostly CO2. So the amount of CO2 is close to a quarter million times as much as on earth.

“Now scientists have discovered that magnetic reconnection also happens on Venus, a planet with no intrinsic magnetic field. The finding, reported today in Science1, suggests that magnetic reconnection may generate auroras on Venus, and could have contributed to the loss of a thick, water-rich atmosphere that scientists believe surrounded the planet during its early history, some 4 billion years ago.”
…
“Just as the solar wind erodes a comet’s tail, it may have also gradually detached molecules, such as water, from Venus’s atmosphere.”http://www.nature.com/news/magnetic-storms-spotted-on-venus-1.10397
Haven’t we all been told that Venus lost its water because of a runaway greenhouse? I never believed it, since greenhouses can not run.

several howlers in the article….NASA is in bad shape…by the way…how do they know the whole atmosphere spins around the planet in four days?…even if you could see past the opaque sulfuric acid clouds…it would seem logical for different layers to move at different speeds

The atmosphere of Earth 4Ba ago was like that of Venus today. It was hot but Earth had water which changed the atmospheric chemistry by dissolving lots of that gas into the water so lowering the surface density and temperature. Remember the bulk of the atmosphere had yet to outgas from the rocks of the mantle at this time. Temperature was higher than today but low enough to encourage simple carbon molecules to recombine to form more complex ones, something carbon is very good at. This took about 1Ba which lead to cyanobacteria which altered the CO2 to O2 and growth. The rest is history.

Owen in GA says:
June 5, 2012 at 2:15 pm
“Unfortunately we are going to be rained out and not get to see it. We were going to set up all the university’s solar telescopes to view it too. However we need the rain more than the view.
Jim G: is .67AU similar to 1AU? I suppose if you round to the nearest whole number it is. The rest is good.”
Owen,
It is. You need to think like an astronomer. Most objects studied are tens, hundreds, thousands, millions or billions of light years away. A few are AU’s away so Venus is about the same distatnce from the Sun as is the Earth when thinking in these terms. Much more was made of this comment than it was worth. The CO2 greenhouse BS was another story, however. Also, at 100 atmospheres and no O2 a person would not only not ignite but would be crushed. Been a long time since my physics class that covered gas temperature and pressure but I would agree with those indicating that such pressures would cause big heat.

true, but being more of an applied electronics guy I think of things in percentage change and 30% can be large (or not depending on circuit tolerances. We’ve had on and off vary by about that much in some circuits and still work. Much more and 1/0 becomes ambiguous = bad.) In computational physics I did a three body problem simulation in which a 1% error was too big to tolerate, so I guess it depends on your starting view and the problem you are solving. I was doing a Goldilocks simulation study on a planet in a binary star system, and 30% error in either irradiance or position would have fried it. (Turns out there are only a few configurations of close in binaries that are stable for a planet in the Goldilocks zone, and they are precarious.)

It is. You need to think like an astronomer. Most objects studied are tens, hundreds, thousands, millions or billions of light years away. A few are AU’s away so Venus is about the same distatnce from the Sun as is the Earth when thinking in these terms.

Ah, so 100ly is a similar distance to 66.6ly. Makes perfect [non]sense.

Jeff Alberts says:
June 7, 2012 at 12:55 pm
It is. You need to think like an astronomer. Most objects studied are tens, hundreds, thousands, millions or billions of light years away. A few are AU’s away so Venus is about the same distatnce from the Sun as is the Earth when thinking in these terms.
“Ah, so 100ly is a similar distance to 66.6ly. Makes perfect [non]sense”
No. But when thinking in LY’s the difference between 1AU and .67AU is miniscule.

From the POVs of galactic clusters or quarks (or even Pluto), very similar indeed; almost indistinguishable.

and Jim G says:
June 8, 2012 at 7:54 am

No. But when thinking in LY’s the difference between 1AU and .67AU is miniscule.

Conspicuous by its absence in these arguments is any notion of scale.
Where I went to school, answers that were off by 30% were not likely to pass. We’re focused on a single star, not the entire galaxy or cosmos.
Discussion of terrestrials planets in the Solar System takes place within the reference frame of the orbit of Mars. On that scale, 25 million miles is highly significant, and the respective orbits of Venus and Earth must be characterized as “dissimilar,” since one is significantly closer to the Sun than the other.

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